Temperature measurement and control of rotating surfaces

ABSTRACT

Means for transferring heat to a moving filament in a filament processing machine wherein a rotatable roller or endless belt contacting the filament is heated from a stationary heat source. For sensing the temperature of the contacting surface of the roller or belt a temperature sensor extends into a pocket formed in a side edge of the roller or belt, the pocket extending parallel with and adjacent to the contacting surface. The sensor is mounted on an intermediate support which in turn is mounted on the machine frame. There is a high thermal resistance between the intermediate support and the sensor and between the support and the frame. The support is in good thermal contact with the ambient.

United States Patent 11 1 1111 3,879,594 Shillito Apr. 22, 1975 1TEMPERATURE MEASUREMENT AND 3.435.171 3/1969 Lohest 2l9/l0.6l A3.529.116 9/1970 Miyagi 2l9/l0.6l CONTROL OF ROTATING SURF CES 3.612.83010/1971 Dienes 219/471 [76] Inventor: Terence Graham Shillito, PO. Box

16 Pastor Manchester- M22 Primary Examiner-Bruce A. Reynolds vLancashll'e- England Attorney, Agent, or Firm-Browdy and Neimark [22]Filed: Sept. 26, 1973 917 [57] ABSTRACT [21] Appl Means for transferringheat to a moving filament in a filament processing machine wherein arotatable roller [30] Foreign Application Priority Data or endless beltcontacting the filament is heated from Sept. 29, 1972 United Kingdom44944/72 Stationary heat Source For Sensing the temperawre of thecontacting surface of the roller or belt a tem- [52] US. Cl. 219/1049;73/351', 219/1061; perature sensor extends into a pocket formed in aside H 219/469 edge of the roller or belt, the pocket extending paral-[51] Int. Cl 1105b 5/06; HOSb 3/02 161 With and j cent o the Contactingsurface. The [58] Field of Search 219/ 10.49, 10.61, 10.77, sensor ismounted on an intermediate pp hi 219/469, 470, 471; 73/351; 338/28, 159in turn is mounted on the machine frame. There is a 7 high thermalresistance between the intermediate sup- 5 References Ci d port and thesensor and between the support and the UNITED STATES PATENTS frame. Thesupport is in good thermal contact with the 3.369.106 2/1968 TFO"219/469 x 3,417,226 12/1968 Thomiszer 219/469 X 7 Claims, 4 DrawingFigures TEMPERATURE MEASUREMENT AND CONTROL OF ROTATING SURFACES Thisinvention relates to heat transferring means.

In many technological processes it is required to transfer heat to arapidly moving filament and to be able to control the heat take-up ofthe filament to within narrow limits. Examples are the drawing andtexturising of synthetic natural-fibre substitutes or alternatives. Itis often convenient to transfer the heat at a rotating roller which alsoimparts the transport energy by having the filament wound round acylindrical surface concentric with the axis of rotation. The criticalprocessing parameter is the temperature of the filament, which due toits intimate contact with the rotating cylindrical surface is atatemperature substantially equal to the temperature of that surface.

Supplying heat energy to the rotating roller by means normally used forstationary members leads to considerable maintenance problems due to thesliding surfaces involved. Methods of overcoming this problem are known,one being to induce electrical currents into the roller, therebytransferring energy through the stationary medium through which theroller rotates without mechanical friction.

In order to be able to control the amount of heat supplied to give thecorrect processing temperature it is necessary to be able to measure thetemperature of the moving filament or some other body whose temperaturehas an unvarying relationship with the filament temperature. Due to thelast qualification the alternatives to the filament temperature will bebodies that are rotating in intimate contact with the filament while itis receiving heat from the rotating roller, and this implies that theheat controlling equipment must either rotate with the roller or thatthe temperature sensing signal must bridge the gap between the rotatingroller and some non-rotating location.

Methods are known which use the radiant energy from either the filamentsurface or some alternative surface that is well coupled thermally tothe filament surface. Radiation occurs across a non-mechanical medium sothat there is again no friction and no maintenance to keep a constantmechanical condition is required. Equipment to measure the temperatureof the source of these radiations based on optical methods of collectionand focussing and spectral analysis are expensive and not appropriatefor multiple industrial use. Methods which sum the radiant energy over asolid angle and convert it to another form of energy which is amenableto measurement are subject to loss errors which may be variable.

It is an object of this invention to reduce the variable heatequilibrium of a simple radiant heat collector that is adaptable for usewith a rotating heated surface.

According to the present invention, there is provided means fortransferring heat to a rapidly moving filament comprising a roller,endless belt or the like conveying element, means for mounting theconveying element on a frame of a filament processing machine, a heatingsource adapted for mounting on the machine frame for supplying heat to asurface of the conveyingelement which, in use, contacts the filament, arecess formed in a side edge of the conveying element which, 1

in use, is adjacent to the frame, the recess extending adjacent to andparallel with the filament contacting surface of the element, and atemperature sensor for extending into the recess without contacting theside walls thereof, wherein the temperature sensor is mounted in goodthermal contact with a structure having a substantial area extendinginto radiation from the side walls of the recess, the structure issupported from an intermediate support which is in good thermal contactwith the ambient atmosphere, there being a high thermal resistancebetween the intermediate support and the structure, and supports of highthermal re sistance are provided for mounting the intermediate supporton the frame of the machine.

The intermediate support may also carry electrically insulatedconnections for any electrical connections between the temperaturesensor and frame related measuring and/or control equipment.

The invention will now be described, by way of example, with referenceto the accompanying drawings, in which:

HO. 1 is an axial section of heat transferring means according to theinvention;

FIG. 2 is a detail of the mounting of a temperature sensor in the heattransferring means of FIG. 1; and

FIGS. 3A and 3B show schematically temperature and thermal resistanceparameters in a known heat transferring means and in the heattransferring means of FIGS. 1 and 2, respectively.

Referring now to FIG. 1 of the drawings, a roller 20 is supported from amain frame 1 of a filament processing machine by means ofa rotatableshaft 2. The roller 20 includes an inner hollow cylinder 3 and a coaxialouter cylinder 4 secured together by means of an annular outer face 5.Inner cylinder 3 is securely and concentrically locked to the rotatableshaft 2 by a nut and washer 6.

For supplying heat to the outer cylinder of the roller 20 a heat source7 is supported on the main frame 1 by an intermediate stationary disc 8and extends into the space between cylinders 3 and 4. Heat source 7 maybe an electrical induction winding or a radiant heater which, whenenergised by alternating current, induces electrical current in theequivalent of a short circuited single turn formed by the outer cylinder4.

At the end of the roller 20 which is adjacent to the frame 1 and disc 8,an annular slot 9 is formed in the cylinder 4. This slot extends axiallyalong the outer cylinder 4 to a location in close proximity to a sectionof the outer surface of the cylinder whose temperature is typical of theheat transferring surface. A gap 10 which allows for rotation ofcylinder 4 relative to disc 8 is made as small as possible so as tominimise the amount of air change in slot 9. This allows the surface ofthe slot 9 to reach the same or nearly the same temperature as the outersurface of cylinder 4.

Projecting into the slot 9 without contacting the cylinder 4 is atemperature sensor 16 which is supported in the manner shown in moredetail in FIG. 2 of the drawings. Referring to FIG. 2, a platform 11which serves as an intermediate support for sensor 16 has a goodtemperature radiating surface so that it remains at substantiallyambient temperature. To further assist in achieving this object theplatform 11 is supported on the disc 8 by pillars 12 of high thermalresistance. Between the pillars 12 a slot 13 is cut in the disc 8 andfrom the platform 11 two supports 14 extend via the slot 13 to a radiantenergy pick-up surface 15 which is located within the annular slot 9.

Mounted on the pick-up surface 15 is the temperature sensor 16. Thesurface 15 is modified by slots 17 to give optimum selection betweenminimum radiation resistance between the surfaces of annular slot 9 andthe pick-up surface 15 and maximum conduction resistance to supports 14.Electrical connection between the sensor 16 and insulated connectors 19on the platform 11 is via electrical connectors I8, which are kept smallin diameter and spiralled to increase their length, thereby reducingthermal shunting.

In the above embodiment the ratio between the temperature drop from theinner surface of slot 9 to temperature sensor 16 and the temperaturedrop from the means of FIGS. 1 and 2, whilst FIG. 3A shows these' twoparameters at locations in a heat transferring means corresponding tothat in FIGS. 1 and 2 except that there is no platform 11, thetemperature sensor 16 being supported directly on the machine frame 1.

Referring first to FIG. 3A, T represents the temperature of the innersurface of slot 9, which is substantially equal to the temperature ofthe outer surface of cylinder 4, and hence the surface temperature of afilament as it leaves the roller 20. T is the temperature of the sensor16, T is the temperature of the machine frame I, R, is the thermalresistance between the inner surface of slot 9 and the sensor 16 and Ris the thermal resistance between sensor 16 and the frame 1.

The relationship between the three temperatures is then given by:

where Rg/R R2 In practice, it is difficult to make R much greater than XR this relationship being indicated in FIG. 3A. Substituting R 10 X R inequation (2) gives,

T" 10/11 x TS) 1/11 X T,, 0.090 TS 0.0909 I) The constant factor 10/ I lX T can be allowed for in calibrating the device but there remain errorsin the reading of T due to the term 1]]! X T,,. In a case where themahine warms up through C. there is an error in the reading of T, of l/ll X 30C 2.73C.

Referring now to FIG. 38, T represents the temperature of the platform11, which is interposed between the sensor 6 and the machine frame 1,and T, is the ambient temperature. R is the thermal resistance betweenthe platform 11 and the frame I and R is the thermal resistance betweenthe platform and the surrounding air due to radiation and contact. Sincethe heat supplied to the heat sink, platform 11, from the inner surfaceof slot 9 and from the machine frame 1 equals the heat lost from theplatform to the ambient air,

Also.

TM 2/ 1 2 S 1/ l 2 R ,(as in equation (2), above) Substituting thevalues for R R R and R given in FIG. 38 gives T T I T T With the knowntransferring means of FIG. 3A it is clear from equation (3) that underconditions where the controlled temperature T is 200C, the ambienttemperature starts at 20C. and rises to 25C and the temperature of themachine frame 1 rises by 30C, the temperature of the sensor T starts atl83.6C. rises to l86.3C. on warm up of the machine. and furtherincreases to l86.80 C with the 5C rise in ambient temperature.

For the heat transferring means of FIG. 3B, equation (6) shows that thecorresponding temperatures recorded by the sensor 16 are 184.5",l84.7and l85.lC.

In practice, a calibration is effected to remove errors under normalconditions, say at T 25C and a rise in T of 30C to 55C. In the case ofthe known device of FIG. 3A this gives rise to a total error of 3.2Cwhen the machine is started up at an ambient temperature of 20C. Theerror reduces to 27C when ambient temperature of 25C is reached. In thedevice of FIG. 3B the total error is 06C at start up, reducing to only02C at an ambient temperature of 25C.

In the heat transferring means of FIGS. 1 and 2 the platform 11 andpick-up surface 15 are made of a high conductivity metal, blackened toenhance its heat radiation properties. The supports 14 are made of metalwith a low cross-sectional area, to increase their thermal resistance,or of ceramic material. The pillars 12 are made of ceramic material andare hollow to allow for fixing by screws to the disc 8.

It will be appreciated that heat transferring means according to theinvention may have an endless band or belt in place of the roller 20 ofFIGS. 1 and 2. In this case a slot corresponding to slot 9 may be formedalong one lateral edge of the belt to receive a temperature sensor.Preferably, the sensor extends into the slot at a location where thebelt contacts a driving roller therefor.

For supplying heat to the roller surface or endless band or belt asource of heat radiation may replace the winding 7. Alternatively, sliprings may be employed to supply heating current to the roller, band orbelt.

I claim:

1. An apparatus for transferring heat to a rapidly moving filamentcomprising:

a conveying element having an endless conveying surface;

means for mounting said element on a frame of a filament processingmachine;

a heating source mounted on said frame for supplying heat to a surfaceof said conveying element which, while in use, contacts said filament;

a recess formed in a side edge of said conveying element, adjacent tosaid frame, said recess extending adjacent and parallel to the surfaceof said conveying element;

a radiant energy pick-up surface disposed within said recess, saidsurface having substantial area and being exposed to radiation from theside walls of said recess;

a temperature sensor mounted in good thermal contact with said pick-upsurface and extending into said recess without contacting the sidewallsthereof;

intermediate support in good thermal contact with the ambient atmospherefor support of said pick-up surface, said support having a high thermalconductivity and there being a high thermal resistance between saidintermediate support and said pickup surface; and

support means of high resistance for mounting said intermediate supporton the frame of the machine.

2. Heat transferring means as claimed in claim 1, wherein the conveyingelement is a hollow, rotatable roller, and the recess is an annularcylindrical recess formed in a cylindrical side wall of the roller.

3. Heat transferring means as claimed in claim 2, wherein the heatingsource extends into the interior of the hollow roller.

' wherein the heating source comprises an electrical winding forinducing heating currents in the conveying element.

7. Heat transferring means as claimed in claim 1, wherein the heatingsource comprises a heating element for supplying radiant heat to theconveying element.

1. An apparatus for transferring heat to a rapidly moving filamentcomprising: a conveying element having an endless conveying surface;means for mounting said element on a frame of a filament processingmachine; a heating source mounted on said frame for supplying heat to asurface of said conveying element which, while in use, contacts saidfilament; a recess formed in a side edge of said conveying element,adjacent to said frame, said recess extending adjacent and parallel tothe surface of said conveying element; a radiant energy pick-up surfacedisposed within said recess, said surface having substantial area andbeing exposed to radiation from the side walls of said recess; atemperature sensor mounted in good thermal contact with said pick-upsurface and extending into said recess without contacting the sidewallsthereof; intermediate support in good thermal contact with the ambientatmosphere for support of said pick-up surface, said support having ahigh thermal conductivity and there being a high thermal resistancebetween said intermediate support and said pick-up surface; and supportmeans of high resistance for mounting said intermediate support on theframe of the machine.
 1. An apparatus for transferring heat to a rapidlymoving filament comprising: a conveying element having an endlessconveying surface; means for mounting said element on a frame of afilament processing machine; a heating source mounted on said frame forsupplying heat to a surface of said conveying element which, while inuse, contacts said filament; a recess formed in a side edge of saidconveying element, adjacent to said frame, said recess extendingadjacent and parallel to the surface of said conveying element; aradiant energy pick-up surface disposed within said recess, said surfacehaving substantial area and being exposed to radiation from the sidewalls of said recess; a temperature sensor mounted in good thermalcontact with said pick-up surface and extending into said recess withoutcontacting the sidewalls thereof; intermediate support in good thermalcontact with the ambient atmosphere for support of said pick-up surface,said support having a high thermal conductivity and there being a highthermal resistance between said intermediate support and said pick-upsurface; and support means of high resistance for mounting saidintermediate support on the frame of the machine.
 2. Heat transferringmeans as claimed in claim 1, wherein the conveying element is a hollow,rotatable roller, and the recess is an annular cylindrical recess formedin a cylindrical side wall of the roller.
 3. Heat transferring means asclaimed in claim 2, wherein the heating source extends into the interiorof the hollow roller.
 4. Heat transferring means as claimed in claim 2,wherein the intermediate support is a platform, the high thermalresistance supports are pillars, and the thermal resistance between theintermediate support and the structure is increased by slots formed inthe structure.
 5. Heat transferring means as claimed in claim 1, whereinthe intermediate support is a platform, the high thermal resistancesupports are pillars, and the thermal resistance between theintermediate support and the said pick-up surface is increased by slotsformed in the said pick-up surfaces.
 6. Heat transferring means asclaimed in claim 1, wherein the heating source comprises an electricalwinding for inducing heating currents in the conveying element.